The present invention relates generally to carburetors for gasoline engines and more particularly to fuel bowls for carburetors and methods of feeding fuel to carburetors.
Carburetors used to supply a fuel/air mix to internal combustion engines rely on a fuel bowl to hold liquid fuel (e.g., gasoline) to be drawn into the carburetor. High-performance engines, such as those used in automobile racing, may put extraordinary demands on the carburetor. Carburetors typically include a main body through which a stream of air from the air intake passes to the manifold, and in which gasoline is fed into the air stream. A fuel bowl holding a reservoir of gasoline is mounted on the main body by a meter block through which a measured flow of gasoline is aspirated from the fuel bowl to the air stream in the main body. One face of the meter block forms a wall of the fuel bowl which is usually immersed about halfway up the face in the gasoline in the fuel bowl. Fuel supply ports in the meter block are positioned to be covered by the gasoline in the fuel bowl so that liquid fuel can be drawn into the meter block and carburetor as needed. It will be understood that there are times when additional liquid fuel will be needed in the fuel bowl and other times when little or no additional fuel is required. Accordingly, fuel bowls typically rely on a float valve to control the level of gasoline in the bowl. As the fuel bowl fills with gasoline, the buoyancy of the float valve causes it to rise on the gasoline until it block a fuel inlet into the fuel bowl. When the level of gasoline drops in the fuel bowl as gasoline is drawn into the carburetor, the float valve moves off the fuel inlet allowing additional gasoline to flow into the fuel bowl.
Upon acceleration in high-performance engines such as those found in automobile racing, immediate and high demand for liquid from the fuel bowl may occur. Conventionally, fuel bowls have relied upon float valves to replenish fuel in the fuel bowl as it is drawn off by carburetor. Valves in general and float valves in particular have finite reaction times, so that there is a small but measureable delay between the rapid intake of gasoline by the carburetor and the flow of replenishing gasoline into the fuel bowl. Moreover, the flow of fuel must go from zero to full flow as the valve opens, which requires some time. In high-performance engines, the delays may be such that there can be a period in which the gasoline level in the fuel bowl falls to a level below that of the fuel supply outlet into the carburetor. As a result, the engine may be starved for fuel for a few moments until the gasoline level in the fuel bowl rises to cover the carburetor fuel supply outlet, producing a significant reduction in engine performance. Starving the engine for fuel can damage the engine. Rapid onset of gasoline flow (i.e., from zero to maximum flow) has been found to produce foaming of the gasoline. If foam is covering the fuel supply outlet to the carburetor, it receives a mixture of gasoline and air rather than solely liquid gasoline. This can also reduce the performance of the engine.
In addition to issues that may be raised by high fuel demand, inertia of the fuel can cause the carburetor and hence the engine to be starved for fuel in situations where the racing automobile experiences significant acceleration. For example as the automobile corners at high speed, substantial acceleration is developed because of the change in direction of the automobile. The inertia of the gasoline in the fuel bowl causes the fuel to move to one side of the bowl in this situation. Often the fuel bowl has two fuel supply outlets to the carburetor, one for each side of the engine. Movement of the fuel to one side of the bowl may uncover one of the fuel supply outlets, causing one side of the engine to be starved for fuel. Conceivably, both fuel supply outlets from the fuel bowl may be uncovered. Reaction of the float valve to this circumstance involves delay and it cannot prevent one or both of the fuel supply outlets from becoming uncovered so no gasoline is delivered to the carburetor.